2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/19023We present a convenient technique describing the condensate in dynamical equilibrium with the thermal cloud, at temperatures close to the critical one. We show that the whole isolated system may be viewed as a single classical field undergoing nonlinear dynamics leading to a steady state. In our procedure it is the observation process and the finite detection time that allow for splitting the system into the condensate and the thermal cloud.4 pages, 4 eps figures, final versionCondensed Mattertext